zoom level listener in google maps v2 in android

问题:

I'm developing an Android app that is supposed to use Google Maps v2. Now i'm stuck at finding when zoom level of map has changed. Can anyone help me?Thanks in advance.

回答1:

Create an implementation of OnCameraChangeListener, and pass an instance of it to setOnCameraChangeListener() of your GoogleMap. Your listener should be called with onCameraChange() whenever the user changes the zoom, center, or tilt. You find out the new zoom level from the CameraPosition object that you are passed.

回答2:

If you're looking for how to determine if the zoom level has changed from the previous zoom level, here's what I'd suggest:

Define an instance variable to keep track of the previous zoom level:

//Initialize to a non-valid zoom value
private float previousZoomLevel = -1.0f;

Also, define an instance variable to let you know if the map is zooming:

private boolean isZooming = false;

When you setup your GoogleMap instance, give it an OnCameraChangeListener...

//mMap is an instance of GoogleMap
mMap.setOnCameraChangeListener(getCameraChangeListener());

Now, define the OnCameraChangeListener that will determine if the zoom level has changed:

public OnCameraChangeListener getCameraChangeListener()
{
    return new OnCameraChangeListener() 
    {
        @Override
        public void onCameraChange(CameraPosition position) 
        {
            Log.d("Zoom", "Zoom: " + position.zoom);

            if(previousZoomLevel != position.zoom)
            {
                isZooming = true;
            }

            previousZoomLevel = position.zoom;
        }
    };
}

Now, you can check the value of isZooming to know if you are changing zoom levels.

Make sure to set

isZooming = false;

after you've completed whatever action relies on knowing if the map is zooming.

回答3:

Since previous answers are based on OnCameraChangeListener and that is deprecated, this answer is based on camera setOnCameraMoveListener.

In this example, I am changing my Map Type when user changes the zoom (using controls or fingers and zooming). If zoom level changes above 18.0, map type changes to MAP_TYPE_HYBRIB and if it goes below 18.0, map type changes to MAP_TYPE_NORMAL.

googleMap.setOnCameraMoveListener(new GoogleMap.OnCameraMoveListener() {
    @Override
    public void onCameraMove() {
        CameraPosition cameraPosition = googleMap.getCameraPosition();
        if(cameraPosition.zoom > 18.0) {
            googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        } else {
            googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
        }
    }
});